Subject + 是 + 锁 + 着 + 的
锁 (suǒ) can function as both a verb meaning "to lock" and a noun meaning "lock." As a verb, it describes the action of securing something. For example, 门是锁着的 means "The door is locked."
出门前别忘了锁门。
Chūmén qián bié wàng le suǒ mén.
Don't forget to lock the door before going out.
这个抽屉锁上了,我找不到钥匙。
Zhège chōuti suǒ shàng le, wǒ zhǎo bú dào yàoshi.
This drawer is locked, and I can't find the key.
她把日记本锁在了柜子里。
Tā bǎ rìjìběn suǒ zài le guìzi lǐ.
She locked her diary in the cabinet.